06-17-2011, 11:42 AM
Just noticed that the Rainier ultra match billet upper is on sale right now for $179 from $219. Good time to pick one up. The description says, "We are holding .0003 or better on all of those measurements. Competitor uppers are between .001 and .003 on the perpendicularity and parallelism". This is impressive if they can really hold .0003".
Also, note that on both the Mega and the Rainier Ultra receivers, not only are they beefed up, but the material is billet 7075 vs forged 6061 on mil spec. 7075 is much stronger at about 8300ksi vs, 4500ksi yield strength and has a higher hardness value at 150 vs 95 on the Brinell hardness scale. Although forged vs machined has much better mechanical properties when compared to the same material type, machined 7075 vs forged 6061 will be much stronger.
Bottom line if you're running a heavy match 24" barrel you better get a beefed up upper receiver to support the cantilevered weight or your accuracy is going to suffer from a flexing upper receiver over time. Personally I'm going to go with a Mega just because I like the idea of the side charge.
Also, note that on both the Mega and the Rainier Ultra receivers, not only are they beefed up, but the material is billet 7075 vs forged 6061 on mil spec. 7075 is much stronger at about 8300ksi vs, 4500ksi yield strength and has a higher hardness value at 150 vs 95 on the Brinell hardness scale. Although forged vs machined has much better mechanical properties when compared to the same material type, machined 7075 vs forged 6061 will be much stronger.
Bottom line if you're running a heavy match 24" barrel you better get a beefed up upper receiver to support the cantilevered weight or your accuracy is going to suffer from a flexing upper receiver over time. Personally I'm going to go with a Mega just because I like the idea of the side charge.